Axial pump assemblies with reciprocating element having ramped cam surfaces

ABSTRACT

Embodiments of the invention provide a pump assembly for a hydraulic tool. The pump assembly can include a reciprocating element that is configured to move between a retracted position and an extended position, a cam surface in the reciprocating element that can engage cam followers, a rotating element that can receive rotational input, and a base that can at least partially surrounds the rotating element. Movement of the cam followers along the cam surface can move the reciprocating element from the retracted position to the extended position.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/875,069, filed Jul. 17, 2019, entitled “AXIAL PUMP ASSEMBLIES,” thecontent of which is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates generally to power tools. Moreparticularly, the present disclosure relates to axial pump designs for ahydraulic power tool.

Hydraulic crimpers and cutters are different types of hydraulic powertools for performing work (e.g., crimping or cutting) on a workpiece. Insuch tools, a hydraulic tool comprising a hydraulic pump is utilized forpressurizing hydraulic fluid and transferring it to a cylinder in thetool. This cylinder causes an extendible piston to be displaced towardsa cutting or crimping head. The piston exerts a force on the head of thepower tool, which may typically include opposed jaws with certaincutting or crimping features, depending upon the particularconfiguration of the power tool. In this case, the force exerted by thepiston may be used for closing the jaws to perform cutting or crimpingon a workpiece (e.g., a wire) at a targeted location.

In some known hydraulic tools, a motor can drive the hydraulic pump byway of a gear reducer or other type of gear assembly. However, there arecertain perceived disadvantages to such known hydraulic tools. Forexample, the motor, hydraulic pump (e.g., one or more pump pistons), andgear assembly can often be complex, heavy, and bulky, particularly inhydraulic tools that are designed for high force applications. In somecases, this can increase the cost to manufacture the hydraulic tool andmight make the hydraulic tool more cumbersome for an operator to use.

Therefore, it may be useful to provide a less complex, lighter weighthydraulic tool that can be used for high force applications or lowerforce applications and that is also more user friendly to the operator.

SUMMARY

Embodiments of the invention provide a pump assembly for a hydraulictool. In one embodiment, the pump assembly includes a reciprocatingelement that is configured to move between a retracted position and anextended position, a cam surface in the reciprocating element engagescam followers, a rotating element receives rotational input, and a baseat least partially surrounds the rotating element. Movement of the camfollowers along the cam surface moves the reciprocating element from theretracted position to the extended position.

In some embodiments, an axial pump assembly includes a reciprocatingblock having ramped radial channels extending radially outward from aninner circumferential surface of the reciprocating block, a sun driverconfigured to be operatively coupled to a motor shaft, ball elementsconfigured to roll on a race portion, each ball element arranged atleast partially within a respective ramped radial channel of the rampedradial channels, and a base at least partially enclosing the sun driverand the ball elements. Movement of the ball elements radially outwardthrough the ramped radial channels drives the reciprocating block awayfrom the base. Movement of the ball elements radially inward through theramped radial channels drives the reciprocating block toward the base.

In some embodiments, an axial pump assembly includes a pump piston, apair of cam follower bearings coupled to opposite ends of the pumppiston, an eccentric bearing configured to drive cycloidal transmissionof the pump piston, a base, and a cycloidal disk configured to beoperatively coupled to a motor shaft of the hydraulic tool by way of theeccentric bearing, the cycloidal disk including a second-stage camportion configured to transmit rotational motion to axial displacementof the pump piston. Rotation of the cycloidal disk and the second-stagecam portion pushes the pair of cam follower bearings and causesreciprocating motion of the pump piston between an extended position anda retracted position.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles ofembodiments of the invention:

FIG. 1A illustrates an exploded view of an axial pump assembly accordingto one embodiment of the invention.

FIG. 1B is a cross-sectional top-down view of the axial pump assembly ofFIG. 1A in a retracted position.

FIG. 1C is a cross-sectional top-down view of the axial pump assembly ofFIG. 1A in an extended position.

FIG. 1D is a corner-sectioned view of the axial pump assembly of FIG. 1Ain the retracted position.

FIG. 1E is a corner-sectioned view of the axial pump assembly of FIG. 1Ain the extended position.

FIG. 1F is a cross-sectional side view of the axial pump assembly ofFIG. 1A operatively coupled to a pump piston and a motor shaft.

FIG. 2A is an exploded view of an axial pump assembly according toanother embodiment of the invention.

FIG. 2B is a corner-sectioned view of the axial pump assembly of FIG. 2Ain a retracted position.

FIG. 2C is a corner-sectioned view of the axial pump assembly of FIG. 2Ain an extended position.

FIG. 2D is a cross-sectional side view of the axial pump assembly ofFIG. 2A operatively coupled to a pump piston and a gearbox.

FIG. 3A is an exploded view of an axial pump assembly according toanother embodiment of the invention.

FIG. 3B is a perspective view of a bottom of a reciprocating disk of theaxial pump assembly of FIG. 3A.

FIG. 3C is a cross-sectional view of the axial pump assembly of FIG. 3Ain a retracted position.

FIG. 3D is a cross-sectional view of the axial pump assembly of FIG. 3Ain an extended position.

FIG. 3E is a cross-sectional side view of the axial pump assembly ofFIG. 3A operatively coupled to a pump piston and a motor shaft.

FIG. 4A is an exploded view of an axial pump assembly according toanother embodiment of the invention.

FIG. 4B is a perspective view of a bottom of a reciprocating disk of theaxial pump assembly of FIG. 4A.

FIG. 4C is a cross-sectional view of the axial pump assembly of FIG. 4Ain a retracted position.

FIG. 4D is a cross-sectional view of the axial pump assembly of FIG. 4Ain an extended position.

FIG. 4E is a cross-sectional side view of the axial pump assembly ofFIG. 4A operatively coupled to a pump piston and a motor shaft.

FIG. 5A is an exploded view of an axial pump assembly according toanother embodiment of the invention.

FIG. 5B is a perspective view of the axial pump assembly of FIG. 5A in aretracted position.

FIG. 5C is a perspective view of the axial pump assembly of FIG. 5A inan extended position.

FIG. 5D is a cross-sectional side view of the axial pump assembly ofFIG. 5A operatively coupled to a pump piston and a motor shaft.

FIG. 6A is an exploded view of an axial pump assembly according toanother embodiment of the invention.

FIG. 6B is a perspective view of the axial pump assembly of FIG. 6A in aretracted position.

FIG. 6C is a perspective view of the axial pump assembly of FIG. 6A inan extended position.

FIG. 6D is a cross-sectional side view of the axial pump assembly ofFIG. 6A operatively coupled to a motor shaft.

FIG. 7A is an exploded view of an axial pump assembly according toanother embodiment of the invention.

FIG. 7B is a perspective view of the axial pump assembly of FIG. 7A in aretracted position.

FIG. 7C is a perspective view of the axial pump assembly of FIG. 7A inan extended position.

FIG. 7D is a cross-sectional side view of the axial pump assembly ofFIG. 7A operatively coupled to a motor shaft.

DETAILED DESCRIPTION

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

As used herein, unless specified or limited otherwise, the terms“mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

The disclosed axial pump assembly will be described with respect to anexample hydraulic tool. However, any one or more example embodiments ofthe disclosed axial pump assembly could be incorporated in alternateforms of a hydraulic tool. Furthermore, one or more example embodimentsof the disclosed axial pump assembly could be used outside of thecontext of a pump system, and could more generally be used as amechanism or mechanisms that generate/generates reciprocation.

In example embodiments, the disclosed axial pump assembly can be part ofa transmission end of a hydraulic power tool. The transmission end ofthe hydraulic tool can include an electric motor configured to drive theaxial pump assembly to cause a pump piston to reciprocate up and down.In practice, the movement of the pump piston can provide hydraulic fluidto a hydraulic fluid passage circuit. Specifically, as the pump pistonmoves down, hydraulic fluid can be withdrawn from a bladder or otherdevice, and as the pump piston moves upward, the withdrawn fluid can bepressurized and delivered by way of the fluid passage circuit to a ramassembly of the hydraulic power tool, in order to drive a cutting orcrimping head of the hydraulic power tool to perform a cutting orcrimping action on a workpiece or other target.

In example embodiments, the axial pump assembly can include areciprocating element, such as a block, a plate, or a disk, that can beoperatively coupled to the pump piston. In an alternative arrangement,the pump piston and the reciprocating element can comprise an integralcomponent. The axial pump assembly can also include a drive element,such as a cycloidal disk or other structure, configured to drivemovement of the reciprocating element. In some embodiments, the driveelement can include its own internal speed reduction, eliminating theneed for a gear reducer assembly. The axial pump assembly can alsoinclude one or more ball or bearing elements arranged between the driveelement and the reciprocating element so that motion and force appliedto the driver causes movement of the ball or bearing elements, which inturn causes movement of the reciprocating element. The axial pumpassembly can also include a base that provides a housing for one or moreother components of the axial pump assembly, such as the one or moreball or bearing elements and the drive element. In some embodiments, thebase can be part of or inserted into a gearbox of the transmission endof the hydraulic tool.

Each of the example embodiments of the disclosed axial pump assemblydescribed herein generate reciprocating motion of the reciprocatingelement (and thus the pump piston) in a different way and provides anadvantage over pump designs in existing tools. For example, theembodiments can be compact (i.e., a smaller form factor) and can reducethe quantity of components needed to achieve desired reciprocatingmotion. Some embodiments can include components that enable internalspeed reduction, eliminating or reducing the need for an external gearreduction assembly. Additionally, in some embodiments, the reciprocatingelement and the drive element can be arranged, and can operate, about acommon axis, and the reciprocating element and the pump piston can besubstantially in line with the motor of the hydraulic tool. In otherwords, the axial pump assembly enables a shaft of the motor to besubstantially coaxial to the line of action of the pump piston that isoperatively coupled to the reciprocating element (and thus substantiallycoaxial to the line of action of the reciprocating element). By havingcomponents of the axial pump assembly in line with the motor, the sizeand complexity of the transmission end of the hydraulic tool can bereduced. In some embodiments, the pump piston can be arranged about thesame common axis as the reciprocating element and the drive element.Further, in some embodiments, even more components of the axial pumpassembly can be arranged about the same common axis.

FIG. 1A illustrates an axial pump assembly 100 that uses radial movementof ball elements 108 to drive a pump piston 118 (see, for example FIG.1F). The axial pump assembly 100 includes a reciprocating block 102, asun driver 104, planetary elements 106, ball elements 108, and a base110. The reciprocating block 102 can be coupled to the pump piston 118by way of a compression spring 112, where the compression spring 112 canbe used to provide force to retract the axial pump assembly 100.Further, the compression spring 112 can push the axial pump assembly 100together, helping to hold the pump assembly 100 together.

The reciprocating block 102 includes four ramped radial channels 114that extend radially outward from an inner circumferential surface 113of the reciprocating block 102. Each channel 114 can take the form of athrough-hole or a blind hole. As a representative example, a singleramped radial channel 114 is labeled in FIG. 1A. In some examples, eachchannel 114 can be ramped downward (i.e., toward the base 110, ratherthan toward a top surface of the reciprocating block 102, as shown).

The sun driver 104 is a cylindrical-shaped element that functions as arotational input and can be operatively coupled (e.g., pressed) directlyto a shaft 120 (see, for example, FIG. 1 F) of a motor of a hydraulictool through a bottom of the base 110. The sun driver 104 can include arace portion 104A and a geared portion 104B. The race portion 104A is aportion of the sun driver 104 on which race portions 106A of theplanetary elements 106 roll. The geared portion 104B is a portion of thesun driver 104 that meshes with geared portions 106B of the planetaryelements 106, creating a planetary speed reducing system. In someembodiments, the sun driver 104 does not include a race portion 104A,but the planetary elements 106 can still roll (i.e., rotate) around thesun driver 104 about a longitudinal axis 122 of the sun driver 104.

The planetary elements 106 are cylindrical-shaped elements, each havinga respective race portion 106A and a respective geared portion 106B. Therace portion 106A is a portion of the planetary element 106 on which theball elements 108 roll. The geared portion 106B functions as a planetarygear for speed reduction. As noted above, the geared portions 106B ofthe planetary elements 106 mesh with the gear portion of the sun driver104. The ball elements 108 can be spherical objects made of metal oranother material.

The base 110 can be a housing that encircles and at least partiallyencloses the sun driver 104, the planetary elements 106, and the ballelements 108. Further, a cylindrical portion 109 of the base 110 caninclude four through-holes 116 that are each separated by a prescribeddistance to space out the ball elements 108. As a representativeexample, a single through-hole 116 is labeled in FIG. 1A. An innercircumferential surface 107 of the base 110 can, in some embodiments,include a geared portion 111 that meshes with the geared portions 106Bof the planetary elements 106 for the purposes of speed reduction. Asshown, the base 110 has a peripheral flange 115 against which an end 117of the reciprocating block 102 can rest or be adjacently positioned whenthe reciprocating block 102 is in a retracted position, as illustratedin FIGS. 1B and 1D, for example.

Although four ramped radial channels 114 and four ball elements 108 areshown, alternative embodiments of the axial pump assembly 100 caninclude more or less of the same or similar channels and ball elements.For example, some embodiments can include two ball elements and twocorresponding ramped radial channels similar to the ball elements 108and ramped radial channels 114 of the axial pump assembly 100.

In operation, the motor rotates the sun driver 104 within thecylindrical portion 109 of the base 110, causing rotation of theplanetary elements 106 about the sun driver 104 (i.e., about thelongitudinal axis 122 of the axial pump assembly 100). Rotation of theplanetary elements 106 pushes the ball elements 108 radially outwardinto the ramped radial channels 114 of the reciprocating block 102. Theinner circumferential surface 113 of the reciprocating block 102surrounds the cylindrical portion 109 of the base 110. The ball elements108 are pushed against the ramped surfaces within the channels 114 atthe through-holes 116, pushing the reciprocating block 102 upwards in adirection substantially parallel to the longitudinal axis 122 and theend 117 of the reciprocating block 102 is moved away from the peripheralflange 115 of the base 110. This motion can thus push the pump piston118 upward. Following this motion, the ball elements 108 retractradially inward within the ramped radial channels 114, toward the sundriver 104, bringing the reciprocating block 102 downwards. As arrangedin the manner shown in FIG. 1A, each of the ball elements 108 can moveradially outward at substantially the same time as one another, and canalso retract radially inward at substantially the same time as oneanother. In this way, the ramped radial channels 114 act as cams and theball elements 108 act as cam followers.

FIG. 1B is a cross-sectional top-down view of the axial pump assembly100 in the retracted position. In the retracted position, the ballelements 108 are retracted into the ramped radial channels 114. In theretracted position, a single ball element 108 can be in contact with oneor more planetary elements 106. The ball elements 108 are positionedradially inward and proximate to one end of the ramped radial channels114 adjacent to the inner circumferential surface 113 of the blockreciprocating block 102. Thus, the reciprocating block 102 is in adownward position and the end 117 of the reciprocating block 102 isadjacent to the peripheral flange 115 of the base 110. Force from thecompression spring 112 can bias the axial pump assembly 100 in theretracted position.

FIG. 1C is a cross-sectional top-down view of the axial pump assembly100 in an extended position. In the extended position, the ball elements108 are pushed radially outward and away from the inner circumferentialsurface 113 of the reciprocating block 102 and into the ramped radialchannels 114. In the extended position, a single ball element 108 is incontact with a single planetary element 106. As the ball elements engagethe ramp of the ramped radial channels 114, the reciprocating block 102is moved upward and the end 117 of the reciprocating block 102 is movedaway from the peripheral flange 115 of the base 110. Thus, thereciprocating block 102 is in an upward, and extended position.

FIGS. 1D and 1E further illustrate the relative position of theplanetary elements 106 and the ball elements 108 with respect to theramped radial channels 114. FIG. 1D is a corner-sectioned view of theaxial pump assembly 100 in the retracted position. FIG. 1E is acorner-sectioned view of the axial pump assembly 100 in the extendedposition.

FIG. 1F is a cross-sectional side view of the axial pump assembly 100where the axial pump assembly 100 is operatively coupled to the pumppiston 118 and the motor shaft 120. The sun driver 104 of the axial pumpassembly 100 can be operatively coupled to the motor shaft 120. Althougha compression spring is not illustrated in FIG. 1F, the schematicrepresentation of the pump piston 118 can include both the compressionspring 112 of FIG. 1A and the pump piston 118. Further, FIG. 1Fillustrates the axial pump assembly 100, the pump piston 118, and themotor shaft 120 are arranged about the longitudinal axis 122.

An advantage of the axial pump assembly 100 is that it combinesmechanisms for reciprocation and speed reduction into a single compactsystem. This is accomplished by combining diameters of planetary gears(i.e., planetary elements 106) as both speed reducers and cams. Anotheradvantage of the axial pump assembly 100 is that one set of cam followerelements (i.e., ball elements 108 of FIG. 1A) drive motion that isperpendicular to the axis of the motor shaft 120 (i.e., axis122)—namely, the radial movement of the ball elements 108 of FIG. 1A—andalso drive reciprocating motion that is in line with axis 122 (i.e.,motion of the reciprocating block 102 of FIG. 1A and the pump piston 118of FIG. 1F). Further, another advantage of the axial pump assembly 100is that the arrangement of the axial pump assembly 100 enables the motorshaft 120 to be coaxial to the line of action of the pump piston 118,which can help provide stable motion of the pump piston 118 duringoperation of the hydraulic tool, as well as reduce the space taken up bythe transmission end of the hydraulic tool.

In some embodiments of the axial pump assembly 100, components of theaxial pump assembly 100 could be configured to reverse the relationshipbetween the motion of the ball elements 108 and the motion of thereciprocating block 102. In particular, the axial pump assembly 100could be configured so that movement (i.e., retraction) of the ballelements 108 radially inward extends the reciprocating block 102 andmovement of the ball elements 108 radially outward retracts thereciprocating block 102. To facilitate this, the cam feature of theaxial pump assembly 100 could be external to the reciprocating block102.

FIG. 2A illustrates another embodiment of an axial pump assembly 200that, similar to the axial pump assembly 100 shown in FIGS. 1A-E, usesradial movement of ball elements 208 to drive a pump piston 220 (see,for example, FIG. 2D). In particular, as shown in FIG. 2A, the axialpump assembly 200 includes a reciprocating block 202, a sun driver 204,a pair of bearings 206, ball elements 208, a base 210, and a retainingring 212. A compression spring is not shown in FIG. 2A, since retractionof the axial pump assembly 200 can be achieved without the use of acompression spring.

The ball elements 208 and the base 210 can take the same or similarforms to the ball elements 108 and the base 110 of the axial pumpassembly 100 of FIG. 1A, respectively. Although the ball elements 208are shown to include four ball elements 208, more or less ball elements208 are possible as well. For example, two ball elements 208 can beused.

The reciprocating block 202 includes four ramped radial channels 214,216 that extend radially outward from an inner circumferential surface213 of the reciprocating block 202. Each channel can take the form of athrough-hole or a blind hole. Within examples, two of the ramped radialchannels 214—namely, a first pair of ramped radial channels 214 that arepositioned radially opposite each other—can be ramped downward (i.e.,toward the base 210, rather than toward a top surface of thereciprocating block 202), whereas the other two of the ramped radialchannels 216—namely, a second pair of ramped radial channels 216 thatare positioned radially opposite each other—can be ramped upward (i.e.,toward a top surface of the reciprocating block 202). In some exampleembodiments where only two ball elements 208 are used, the reciprocatingblock 202 might include two ramped radial channels 214 that arepositioned opposite each other, each of which might be ramped downward.

The sun driver 204 is a partially cylindrical-shaped element thatfunctions as a rotational input and can be operatively coupled (e.g.,pressed) to a shaft 224 (see, for example, FIG. 2D) of a motor of thehydraulic tool through a bottom of the base 210. The sun driver 204 canbe coupled directly to the shaft 224 or by way of a gearbox. Further,the sun driver 204 can include a cam groove 218 (i.e., a race or track)in which the ball elements 208 roll. As such, the sun driver 204 can actas a cam. In some examples, the cam groove 218 can be sinusoidal-shapedor shaped in some other manner that coordinates the timing of themovement of the ball elements 208—namely, so that two of the ballelements 208 that are positioned radially opposite each other moveradially outward at substantially the same time as the other two of theball elements 208 that are positioned radially opposite each otherretract radially inward. In alternative embodiments, other groovedesigns and ramping arrangements for the radial channels are possible aswell to achieve the same desired reciprocating movement up and down. Thesun driver 204 and its cam groove 218 drive movement of the ballelements 208, but a geared driver and planetary elements are not usedfor speed reduction. Thus, speed reduction mechanisms that are externalto the axial pump assembly 200 might be required.

The pair of bearings 206 can be configured to support cam forces. Moreor less bearings 206 could be used for the same purpose in alternativeembodiments. The retaining ring 212 can be configured to hold the pairof bearings 206 axially within the base 210.

In operation, the motor rotates the sun driver 204, pushing two of theball elements 208 (i.e., two radially opposing ball elements) radiallyoutward into the first pair of ramped radial channels 214 of thereciprocating block 202 and against the ramped surfaces within thechannels. This pushes the reciprocating block 202 upwards in a directionsubstantially parallel to the common axis 226 and away from a peripheralflange 215 of the base 210. At substantially the same time as two of theball elements 208 are being pushed radially outward as part of thismotion, the other two of the ball elements 208 (i.e., the other tworadially opposing ball elements) retract radially inward through thesecond pair of ramped radial channels 216 of the reciprocating block 202and toward the sun driver 204. This motion can thus push the pump piston220 upward. Following this motion, the two ball elements 208 that werepushed radially outward then retract inward and, at substantially thesame time, the two ball elements 208 that were retracted radially inwardare then pushed radially outward, bringing the reciprocating block 202downwards.

FIG. 2B is a corner-sectioned view of the axial pump assembly of FIG. 2Ain a retracted position in which the reciprocating block 202 is in adownward position. FIG. 2C is a corner-sectioned view of the axial pumpassembly of FIG. 2A in an extended position in which the reciprocatingblock 202 is in an upward position.

FIG. 2D is a cross-sectional side view of the axial pump assembly 200where the axial pump assembly 200 is operatively coupled to a pumppiston 220 and a gearbox 222. FIG. 2D also depicts a motor shaft 224that is operatively coupled to the axial pump assembly 200 (i.e., to thesun driver 204) by way of the gearbox 222. The gearbox 222 can also becoupled to the base 210 of the axial pump assembly 200. Further, FIG. 2Ddepicts the axis 226 about which the axial pump assembly 200, the pumppiston 220, and the motor shaft 224 are arranged.

An advantage of the axial pump assembly 200 is that it uses one set ofcam follower elements (i.e., ball elements 208 of FIG. 2A) to drivemotion that is both perpendicular to the axis of the motor shaft 224(i.e., axis 226)—namely, the radial movement of the ball elements208—and also to drive reciprocating motion that is in line with axis 226(i.e., motion of the reciprocating block 202 of FIG. 2A and the pumppiston 220 of FIG. 2D). Another advantage of the axial pump assembly 200is that the cam groove 218 of the sun driver 204 enables synchronizationof the perpendicular and reciprocating motions within a single compactsystem. Further, another advantage of the axial pump assembly 200 isthat the arrangement of the axial pump assembly 200 enables the motorshaft 224 to be coaxial to the line of action of the pump piston 220,which can help provide stable motion of the pump piston 220 duringoperation of the hydraulic tool, as well as reduce the space taken up bythe transmission end of the hydraulic tool. Yet another advantage of theaxial pump assembly 200 is that it has automatic retraction without theneed for a compressions spring.

In some embodiments of the axial pump assembly 200, components of theaxial pump assembly 200 could be configured to reverse the relationshipbetween the motion of the ball elements 208 and the motion of thereciprocating block 202. In particular, the axial pump assembly 200could be configured so that movement (i.e., retraction) of the ballelements 208 radially inward extends the reciprocating block 202 andmovement of the ball elements 208 radially outward retracts thereciprocating block 202. To facilitate this, the cam feature of theaxial pump assembly 200 could be external to the reciprocating block202.

FIG. 3A illustrates another embodiment of an axial pump assembly 300 fordriving motion of a pump piston 318 (see, for example, FIG. 3E). Theaxial pump assembly 300 includes a reciprocating disk 302, a cycloidaldisk 304, an eccentric bearing 306, a pair of ball elements 308, and abase 310. In some embodiments, a compression spring (not shown) or othercomponent can be used to bias the reciprocating disk 302 in a directiontoward the pair of ball elements 308 and also to help hold the axialpump assembly 300 together. Further, in some embodiments, additionalcomponents not shown in FIG. 3A might be included to improve andmaintain stability of the pair of ball elements 308.

As shown in FIG. 3B, the reciprocating disk 302 can include a firstannular cam groove 312 disposed in a bottom surface 313 of thereciprocating disk 302. The pair of ball elements 308 can roll in thefirst annular cam groove 312. In some examples, the first annular camgroove 312 can be shaped to receive a portion of the pair of ballelements 308. Further, the first annular cam groove 312 can be taperedso that the deepest portions of the first annular cam groove 312 contactthe pair of ball elements 308 at substantially the same time, causingthe reciprocating disk 302 to be in a retracted position. Still further,the first annular cam groove 312 can be tapered so that the shallowestportions of the first annular cam groove 312 contact the pair of ballelements 308 at substantially the same time, causing the reciprocatingdisk 302 to be in an extended position. The retracted position is shownin the cross-sectional view of the axial pump assembly 300 of FIG. 3C.The extended position is shown in the cross-sectional view of the axialpump assembly 300 of FIG. 3D.

Referring back to FIG. 3A, the cycloidal disk 304 functions as arotational input and can be operatively coupled to a shaft 320 (see, forexample, FIG. 3E) of the motor of the hydraulic tool through a bottom ofthe base 310. For example, the cycloidal disk 304 can be coupled to theshaft 320 by way of the shaft 320 being pressed to the eccentric bearing306. Additionally, the cycloidal disk 304 can include a pair ofthrough-holes 315 configured to maintain the pair of ball elements 308in the first annular cam groove 312, as well as in the second annularcam groove 314 of the base 310, and also to rotationally push the pairof ball elements 308 during operation. Further, the cycloidal disk 304can have a geared periphery 317 for meshing with base pins 316 of thebase 310. As so arranged, the cycloidal disk 304 can provide speedreduction. The cycloidal disk 304 can also include a through-hole 319configured to encircle the eccentric bearing 306. The eccentric bearing306 can be configured to generate rotational eccentricity that drivescycloidal transmission. The pair of ball elements 308 can be configuredto act as cam followers that transmit axial forces between thereciprocating disk 302 and the base 310.

The base 310 can be configured to act as housing for other components ofthe axial pump assembly 300 and to provide a reaction force to drive thecycloidal disk 304. As noted above, the base 310 can include the secondannular cam groove 314 which, unlike the first annular cam groove 312might have a uniform depth.

In operation, rotation of the shaft rotates the cycloidal disk 304, thusrotationally pushing the pair of ball elements 308. The movement of thepair of ball elements 308 in the first annular cam groove 312 thuscauses the reciprocating disk 302 to move up and down between theretracted position and the extended position.

FIG. 3E is a cross-sectional side view of the axial pump assembly 300where the axial pump assembly 300 is operatively coupled to the pumppiston 318 and the motor shaft 320. As mentioned above, the cycloidaldisk 304 of the axial pump assembly 300 can be operatively coupled tothe motor shaft 320. Although a compression spring is not depicted inFIG. 3E, the block representing the pump piston 318 can represent boththe compression spring and the pump piston 318. Further, FIG. 3E depictsan axis 322 about which the axial pump assembly 300, the pump piston318, and the motor shaft 320 are arranged.

An advantage of the axial pump assembly 300 is that it combinesmechanisms for reciprocation and speed reduction into a single compactsystem requiring less parts for operation than in some existing systems.This is accomplished by using cam followers (i.e., ball elements 308 ofFIG. 3A) that interact with a cam of a reciprocating element (i.e., thefirst annular cam groove 312 of reciprocating disk 302). Further,another advantage of the axial pump assembly 300 is that the arrangementof the axial pump assembly 300 enables the motor shaft 320 to be coaxialto the line of action of the pump piston 318, which can help reduce thespace taken up by the transmission end of the hydraulic tool.

FIG. 4A illustrates another embodiment of an axial pump assembly 400 fordriving motion of a pump piston 424 (see, for example, FIG. 4E). Inparticular, the axial pump assembly 400 uses a tangential cam to createaxial motion. The axial pump assembly 400 includes a reciprocating disk402, a cycloidal disk 404, an eccentric bushing 406, a pair of camroller bushings 408, a base 410, four second-stage bushings 412, asecond-stage disk 414, and a bearing 416. In some embodiments, acompression spring (not shown in FIG. 4A) or other component can be usedto bias the reciprocating disk 402 in a direction toward the pair of camroller bushings 408 and also to help hold the axial pump assembly 400together.

As shown in FIG. 4B, the reciprocating disk 402 can include a cam groove418 disposed on or in an inner circumferential surface 413 of thereciprocating disk 402. By way of the cam groove 418, the reciprocatingdisk 402 interacts axially with the pair of cam roller bushings 408 tocreate reciprocating motion of the reciprocating disk 402 between aretracted position and an extended position. The retracted position isshown in the cross-sectional view of the axial pump assembly 400 of FIG.4C. The extended position is shown in the cross-sectional view of theaxial pump assembly 400 of FIG. 4D.

Referring back to FIG. 4A, the cycloidal disk 404 functions as arotational input and can be operatively coupled to a shaft 426 (see, forexample, FIG. 4E) of the motor (not shown) of the hydraulic tool througha bottom of the base 410. For example, the cycloidal disk 404 can becoupled to the shaft 426 by way of the shaft 426 being pressed to theeccentric bushing 406. The cycloidal disk 404 can be positioned betweenthe reciprocating disk 402 and the second-stage disk 414. Additionally,the cycloidal disk 404 can include five through-holes 415, four of whichare configured to receive the four second-stage bushings 412 and fourdisk pins 420 protruding from the second-stage disk 414, and one ofwhich is configured for receiving the eccentric bushing 406. Theeccentric bushing 406 can be configured to generate rotationaleccentricity that drives cycloidal transmission. Further, the cycloidaldisk 404 can have a geared periphery for meshing with base pins 422 ofthe base 410 and providing speed reduction.

As so arranged, the cycloidal disk 404, in operation, can converteccentric motion to rotational motion—namely, rotational motion thatdrives rotation of the second-stage disk 414. Each cam roller bushing ofthe pair of cam roller bushings 408 can include a through-hole, a blindhole, or other manner of coupling the cam roller bushing 408 to one ofthe four disk pins 420. Thus, in operation, the rotational motion of thesecond-stage disk 414 is translated to the pair of cam roller bushings408, which in turn interact axially with the cam groove 418 of thereciprocating disk 402, causing the reciprocating disk 402 to move upand down between the retracted position and the extended position.

Furthermore, the four second-stage bushings 412 can be slid around orotherwise coupled to the four disk pins 420 and are configured to reducefrictional resistance between the four disk pins 420 and the cycloidaldisk 404. Similarly, the bearing 416 can encircle the second-stage disk414 and is configured to reduce frictional resistance between the base410 and the second-stage disk 414. The base 410 can be configured to actas housing for other components of the axial pump assembly 400 and toprovide a reaction force to drive the cycloidal disk 404.

FIG. 4E is a cross-sectional side view of the axial pump assembly 400where the axial pump assembly 400 is operatively coupled to the pumppiston 424 and the motor shaft 426. As mentioned above, the cycloidaldisk 404 of the axial pump assembly 400 can be operatively coupled tothe motor shaft 426. Although a compression spring is not depicted inFIG. 4E, the block representing the pump piston 424 can represent boththe compression spring and the pump piston 424. Further, FIG. 4E depictsan axis 428 about which the axial pump assembly 400, the pump piston424, and the motor shaft 426 are arranged.

An advantage of the axial pump assembly 400 is that it combinesmechanisms for reciprocation and speed reduction into a single system.This is accomplished by combining a cam system with a cycloidal reducer.Further, another advantage of the axial pump assembly 400 is that thearrangement of the axial pump assembly 400 enables the motor shaft 426to be coaxial to the line of action of the pump piston 424, which canhelp reduce the space taken up by the transmission end of the hydraulictool and can also help maintain stable motion.

In alternative embodiments, a planetary gear system could beincorporated with the axial pump assembly 400. In other alternativeembodiments, more or less disk pins, base pins, and second-stagebushings could be used. For example, in one embodiment, no second-stagebushings might be used.

FIG. 5A illustrates an exploded view of another embodiment of an axialpump assembly 500 for driving motion of a pump piston 524 (See, forexample FIG. 5D). In particular, the axial pump assembly 500 uses anaxial cam to create motion. The axial pump assembly 500 includes areciprocating plate 502, a cycloidal disk 504, an eccentric bushing 506,a pair of cam follower bushings 508, a base 510, a ring element 512,five second-stage bushings 514, and a bearing 516. In some embodiments,a compression spring (not shown in FIG. 5A) or other component can beused to bias the reciprocating plate 502 in a retracted position andalso to help hold the axial pump assembly 500 together. Thereciprocating plate 502 can include two opposing side members aroundwhich the pair of cam follower bushings 508 are positioned.

The cycloidal disk 504 functions as a rotational input and can beoperatively coupled to a shaft 526 (see, for example, FIG. 5D) of themotor (not shown) of the hydraulic tool through a bottom of the base510. For example, the cycloidal disk 504 can be coupled to the shaft byway of the shaft being pressed to the eccentric bushing 506. Thecycloidal disk 504 can be mounted to the base 510 by way of five basepins 518 protruding from the base 510 and can be mounted so that thecycloidal disk 504 is positioned between the reciprocating plate 502 andthe bottom of the base 510. Additionally, the cycloidal disk 504 caninclude six through-holes 515, five of which are configured to receivethe five second-stage bushings 514 and the five base pins 518, and oneof which is configured for receiving the eccentric bushing 506. Theeccentric bushing 506 can be configured to generate rotationaleccentricity that drives cycloidal transmission. Further, the cycloidaldisk 504 can have a geared periphery 517 for meshing with outer pins 520of the ring element 512.

In addition, the ring element 512 can include an annular cam track 522protruding from the ring element 512 and along which the pair of camfollower bushings 508 roll to produce reciprocating motion. The annularcam track 522 can be tapered such that the deepest portions of theannular cam track 522 contact the pair of cam follower bushings 508 atsubstantially the same time, thereby causing the reciprocating plate 502to be in a retracted position. Further, the annular cam track 522 can betapered such that the shallowest portions of the annular cam track 522contact the pair of cam follower bushings 508 at substantially the sametime, causing the reciprocating plate 502 to be in an extended position.The retracted position is shown in the perspective view of the axialpump assembly 500 of FIG. 5B. The extended position is shown in theperspective view of the axial pump assembly 500 of FIG. 5C.

Through the meshing of the outer pins 520 with the geared periphery ofthe cycloidal disk 504, the ring element 512 receives rotational motionfrom the cycloidal disk 504. This rotational motion is then translatedto reciprocating motion of the reciprocating plate 502 between theretracted position and the extended position by way of the pair of camfollower bushings 508 rolling on the annular cam track 522.

Furthermore, the five second-stage bushings 514 can be slid around orotherwise coupled to the five base pins 518 and are configured to reducefrictional resistance between the five base pins 518 and the cycloidaldisk 504. Similarly, the bearing 516 can encircle the ring element 512and be positioned between the ring element 512 and the side wall of thebase 510. The bearing 516 is configured to reduce frictional resistancebetween the base 510 and the ring element 512. For simplicity, thebearing 516 is not shown in FIGS. 5B and 5C. Moreover, the base 510 canbe configured to act as housing for other components of the axial pumpassembly 500 and to provide a reaction force to drive the cycloidal disk504 and the ring element 512.

As so arranged, the cycloidal disk 504, in operation, can converteccentric motion to rotational motion—namely, motion that drivesrotation of the ring element 512. In particular, rotation of the motorshaft causes the cycloidal disk 504 to oscillate eccentrically, back andforth in a circular motion. Reaction forces between the cycloidal disk504 and the five second-stage bushings 514 (or, in an embodiment whereno bushings a present, then between the cycloidal disk 504 and the fivebase pins 518) cause the geared periphery of the cycloidal disk 504 topush on the outer pins 520, driving rotation of the ring element 512and, in turn, reciprocating motion of the reciprocating plate 502.

FIG. 5D is a cross-sectional side view of the axial pump assembly 500where the axial pump assembly 500 is operatively coupled to the pumppiston 524 and the motor shaft 526. As mentioned above, the cycloidaldisk 504 of the axial pump assembly 500 can be operatively coupled tothe motor shaft 526. Although a compression spring is not depicted inFIG. 5D, the block representing the pump piston 524 can represent boththe compression spring and the pump piston 524. Further, FIG. 5D depictsan axis 528 about which the axial pump assembly 500, the pump piston524, and the motor shaft 526 are arranged.

An advantage of the axial pump assembly 500 is that it combinesmechanisms for reciprocation and speed reduction into a single system.This is accomplished by combining a cam system with a cycloidal reducer.Further, another advantage of the axial pump assembly 500 is that thearrangement of the axial pump assembly 500 enables the motor shaft 526to be coaxial to the line of action of the pump piston 524, which canhelp reduce the space taken up by the transmission end of the hydraulictool and can also help maintain stable motion. The axial pump assembly500 also differs from some existing arrangements in that the cycloidaldisk 504 oscillates eccentrically instead of rotating.

In alternative embodiments, a planetary gear system could beincorporated with the axial pump assembly 500. In other alternativeembodiments, more or less disk pins, base pins, and second-stagebushings could be used. For example, in one embodiment, no second-stagebushings might be used.

FIGS. 6A-6C and 7A-7C relate to another form that an axial pump assemblymight take—particularly, where reciprocating motion is generated by apump piston that is transverse to other components of the axial pumpassembly and perpendicular to an axis about which a shaft of the motor(and thus, the cycloidal disk) rotates. Similar to the embodimentsdescribed above, each of the example axial pump assemblies shown inFIGS. 6A-6C and 7A-7C are compact and combine speed reduction andreciprocating motion in a single mechanism.

FIG. 6A illustrates an exploded view of another embodiment of an axialpump assembly 600 for driving motion of a pump piston 602. In additionto the pump piston 602, the axial pump assembly 600 includes a cycloidaldisk 604, an eccentric bearing 606, a pair of cam follower bearings 608,a base 610, a second-stage cam 612 operatively coupled to the cycloidaldisk 604, five second-stage bushings 614, and a load supporting bearing616. Also shown is a manifold 618, which can house hydraulic components(e.g., check valves) and through which hydraulic fluid can be pumped.Although FIG. 6A shows the manifold 618, the manifold 618 might beconsidered to not be a component of the axial pump assembly 600 in someembodiments.

The pump piston 602 is bi-diametral and transverse, comprising a firstsection 603 having a first diameter and a second section 605 having asecond diameter that is larger than the first diameter. The twodiameters enable hydraulic fluid to be pumped through the manifold 618.The pump piston 602 is arranged partially within the manifold 618.

The cycloidal disk 604 functions as a rotational input and can beoperatively coupled to a shaft 624 (see, for example, FIG. 6D) of themotor (not shown) of the hydraulic tool through a bottom of the base610. For example, the cycloidal disk 604 can be coupled to the shaft byway of the shaft being pressed to the eccentric bearing 606. Thecycloidal disk 604 can be positioned between the second-stage cam 612and the bottom of the base 610. Additionally, the cycloidal disk 604 caninclude six through-holes 615, five of which are configured to receivethe five second-stage bushings 614 and five cam pins 620 protruding fromthe bottom of the second-stage cam 612, and one of which is configuredfor receiving the eccentric bearing 606. The eccentric bearing 606 canbe configured to generate rotational eccentricity that drives cycloidaltransmission. Further, the cycloidal disk 604 can have a gearedperiphery 617 for meshing with base pins 622 of the base 610. As soarranged, the cycloidal disk 604, in operation, provides speed reductionand can convert eccentric motion to rotational motion—namely, rotationalmotion that drives rotation of the second-stage cam 612.

The pair of cam follower bearings 608 are coupled to the ends of thepump piston 602. Rotational motion of the second-stage cam 612 pushesthe pair of cam follower bearings 608, which moves the pump piston 602back and forth between a retracted position and an extended position.The retracted position is shown in the perspective view of the axialpump assembly 600 of FIG. 6B. The extended position is shown in theperspective view of the axial pump assembly 600 of FIG. 6C. In FIGS. 6Band 6C, the manifold 618 is sectioned in order to show the position ofthe pump piston 602.

Furthermore, the five second-stage bushings 614 can be slid around orotherwise coupled to the five cam pins 620 and are configured totransmit rotational force from the cycloidal disk 604 to thesecond-stage cam 612. In addition, the load supporting bearing 616 canbe slid around or otherwise coupled to the manifold 618 and isconfigured to support loads from the second-stage cam 612.

FIG. 6D is a cross-sectional side view of the axial pump assembly 600where the axial pump assembly 600 is operatively coupled to the motorshaft 624. As mentioned above, the cycloidal disk 604 of the axial pumpassembly 600 can be operatively coupled to the motor shaft 624. Further,FIG. 6D depicts a first axis 626 about which the motor shaft 624 rotates(i.e., the longitudinal axis of the motor shaft 624) and about which thecycloidal disk 604 is arranged. FIG. 6D also depicts a second axis 628that is substantially perpendicular to the first axis 626 and alongwhich the pump piston 602 moves (i.e., the longitudinal axis of the pumppiston 602). In some embodiments, the second axis 628 can be centered onthe first axis 626 (e.g., so that the longitudinal axis of the motorshaft 624 and the longitudinal axis of the pump piston 602 substantiallyintersect).

An advantage of the axial pump assembly 600 is that it combinesmechanisms for reciprocation and speed reduction into a compact system.This is accomplished by combining a cam system with a cycloidal disk(i.e., cycloidal disk 604 of FIG. 6A) that also acts as a speed reducer.Further, another advantage of the axial pump assembly 600 is that areturn spring is not necessary for reciprocating motion, since thepoints at which the pair of cam followers 608 of FIG. 6A contact thesecond-stage cam 612 are offset from the second axis 628. Anotheradvantage of the axial pump assembly 600 is that the cam feature beingseparate from the cycloidal element allows for smooth interaction butmight require a central load supporting bearing. In other embodiments,more or less second-stage bushings could be used. For example, in oneembodiment, no second-stage bushings might be used.

FIG. 7A illustrates an exploded view of another embodiment of an axialpump assembly 700 for driving motion of a pump piston 702. In additionto the pump piston 702, the axial pump assembly 700 includes a cycloidaldisk 704, an eccentric bearing 706, a pair of cam follower bearings 708,and a base 710. Also shown is a manifold 712, which can house hydrauliccomponents (e.g., check valves) and through which hydraulic fluid can bepumped. Although FIG. 7A shows the manifold 712, the manifold 712 mightbe considered to not be a component of the axial pump assembly 700 insome embodiments.

The axial pump assembly 700 of FIG. 7A operates similarly to the axialpump assembly 600 of FIG. 6A, except the cycloidal disk 704 isintegrated with a second-stage cam (e.g., second stage cam 612 of FIG.6A). In other words, as opposed to having two separate components—acycloidal disk and a second-stage cam, the cycloidal disk 704 of FIG. 7Ais a single component including a second-stage cam portion 714 and ageared portion 716. The eccentric bearing 706, the pair of cam followerbearings 708, and the base 710 can each be configured the same as theircorresponding component described above with respect to FIG. 6A.

In operation, rotational motion of the second-stage cam portion 714 ofthe rotating cycloidal disk 704 pushes the pair of cam follower bearings708, which moves the pump piston 702 back and forth between a retractedposition and an extended position. The retracted position is shown inthe perspective view of the axial pump assembly 700 of FIG. 7B. Theextended position is shown in the perspective view of the axial pumpassembly 700 of FIG. 7C. In FIGS. 7B and 7C, the manifold 712 issectioned in order to show the position of the pump piston 702.

FIG. 7D is a cross-sectional side view of the axial pump assembly 700where the axial pump assembly 700 is operatively coupled to a motorshaft 718. As mentioned above, the cycloidal disk 704 of the axial pumpassembly 700 can be operatively coupled to the motor shaft 718. Further,FIG. 7D depicts a first axis 720 about which the motor shaft 718 rotates(i.e., the longitudinal axis of the motor shaft 718) and about which thecycloidal disk 704 is arranged. FIG. 7D also depicts a second axis 722that is substantially perpendicular to the first axis 720 and alongwhich the pump piston 702 moves (i.e., the longitudinal axis of the pumppiston 702). In some embodiments, the second axis 722 can be centered onthe first axis 720 (e.g., so that the longitudinal axis of the motorshaft 718 and the longitudinal axis of the pump piston 702 substantiallyintersect).

An advantage of the axial pump assembly 700 is that it combinesmechanisms for reciprocation and speed reduction into a compact systemrequiring less parts for operation than in some existing systems. Thisis accomplished by combining a cam system with a cycloidal disk (i.e.,cycloidal disk 704 of FIG. 7A) that also acts as a speed reducer.Further, another advantage of the axial pump assembly 700 is that areturn spring is not necessary for reciprocating motion, since thepoints at which the pair of cam followers 708 of FIG. 7A contact thesecond-stage cam portion 714 are offset from the second axis 722.Another advantage of the axial pump assembly 700 is that the cam featureis merged with the cycloidal element, thus eliminating the need for acentral load supporting bearing.

By the term “substantially” or “about” used herein, it is meant that therecited characteristic, parameter, value, or geometric planarity neednot be achieved exactly, but that deviations or variations, includingfor example, tolerances, measurement error, measurement accuracylimitations and other factors known to skill in the art, may occur inamounts that do not preclude the effect the characteristic was intendedto provide.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the invention.Various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other embodiments without departing from the spirit orscope of the invention. Thus, the invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

The invention claimed is:
 1. A pump assembly for a hydraulic tool, thepump assembly comprising: a reciprocating element configured to movebetween a retracted position and an extended position; a cam surface inthe reciprocating element that engages cam followers, the cam surfacebeing a ramped radial channel including a hole extending radiallyoutward from an inner circumferential surface of the reciprocatingelement; a rotating element that receives a rotational input, each ofthe rotating element and the rotational input concentric with thereciprocating axis of the reciprocating element; and a base that atleast partially surrounds the rotating element; movement of the camfollowers along the cam surface moving the reciprocating element fromthe retracted position to the extended position.
 2. The pump assembly ofclaim 1, wherein the reciprocating element and the rotating element arepositioned along a common axis.
 3. The pump assembly of claim 1, whereinthe cam followers are balls that engage a sloped surface.
 4. The pumpassembly of claim 3, wherein the sloped surface is formed in thereciprocating element.
 5. The pump assembly of claim 1, wherein the camsurface is one of a plurality of cam surfaces extending radially outwardfrom an inner circumferential surface of the reciprocating element. 6.The pump assembly of claim 1, wherein the rotating element is a sundriver that includes a race portion.
 7. The pump assembly of claim 1,wherein the rotating element includes a geared portion that providesspeed reduction from the rotational input.
 8. The pump assembly of claim1, wherein the base includes a plurality of pins extending therefromthat are dimensioned to mesh with a geared periphery of the rotatingelement.
 9. The pump assembly of claim 1, wherein the reciprocatingelement is positioned along a first axis, the rotating element ispositioned along a second axis, and the first axis is perpendicular tothe second axis.
 10. The pump assembly of claim 1, wherein the rotatingelement is configured to be operatively coupled to a pump piston of ahydraulic tool.